The staff of the Neuropathology Core has a central role in our Alzheimer's Disease Research Center (ADRC). They perform neuropathological/neurobiological evaluations of the brains of human subjects, help with the assessments of transgenic animal models, train physicians/scientists in issues relevant to neurodegenerative diseases, and collaborative with the medical and research communities in diagnostic/research activities relevant to aging and alzheimer's disease (AD). Investigators supported by this Core have a longstanding history of productive collaborations in basic and clinical research on age- associated neurodegenerative disorders. This Core has several specific goals: to arrange/conduct autopsies and establish diagnoses in controls and demented subjects, including individuals from the Baltimore Longitudinal Study of Aging (BLSA); measure pathological-morphometric- neurochemical variables in brain tissue; to facilitate analyses of transgenic mouse models of neurodegenerative disorders; to validate a system for grading the pathological severity in cases of AD; and to obtain, store and distribute human brain tissues for intramural and extramural basic research. To accomplish these goals, the staff maintains the Brain Resource Center (BRC), a histology/immunocytochemistry laboratory, a quantitative morphometry/stereology laboratory, and facilities for neurochemical/receptor autoradiographic analyses. The BRC serves as a repository of fixed and frozen tissues prepared for research from >780 subjects, including controls, cases of AD, and cases with other types of dementia. The functions of this Core have been enhanced by several new developments. The autopsy program has been expanded to include greater numbers of control subjects, minority subjects, and cases of Parkinson's disease with and without dementia. Serum and cerebrospinal fluid samples are stored for future studies. A stereology unit has been established for the unbiased quantitation of neurons/synapses. Finally, because of the importance of genetic factors in neurodegenerative disorders, the faculty of this Core assists in the analyses of transgenic mice, thus taking advantage of our expertise in investigations of animal models of neurodegenerative disease. Through these manifold activities. This Core acts to support and coordinate the evaluation of clinical and experimental material, thereby facilitating key diagnostic and research capacities of our ADRC.